On the origin of elevated surface ozone concentrations at Izana Observatory, Tenerife during late March 1996

• Published in: Geophysical Research Letters
• Main Authors: Kentarchos, Anastasios S., Roelofs, Geert-Jan, Lelieveld, Johannes, Cuevas Agulló, Emilio
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2000
• Subjects: Surface ozone; Concentrations; Variability; Stratosphere-troposphere exchange; North Atlantic
• Online Access: https://hdl.handle.net/20.500.11765/2223

The origin of relatively high surface ozone concentrations measured at Izana Observatory (Canary Islands) during the end of March 1996 is studied using a coupled chemistry-GCM (ECHAM4) at T63 resolution (1.875° × 1.875°). Meteorological fields (geopotential height, potential vorticity, specific humidity), and a model-simulated stratospheric ozone tracer as well as 3-D back trajectories, show the stratospheric origin of these relatively high surface ozone values caused by cross-tropopause exchange at the western flank of an upper level trough/cut-off low (COL) over the extratropical North-Atlantic Ocean. The good agreement between observations and model results (within 10–15%) indicates that the high resolution chemistry-GCM is a useful tool towards the understanding of natural sources controlling background surface ozone variability. The results underscore the importance of stratosphere-troposphere exchange (STE) during late winter/early spring for lower free tropospheric ozone at subtropical latitudes.